Compound archery bows use eccentric wheels or cams (either two wheels or two cams) along with connecting cables and a bow string to control the force required to draw the bow and store energy in the bow limbs. An eccentric wheel or cam is mounted to each bow limb tip and a cable connects each wheel or cam to the opposite limb tip. The bow string connects the two wheels or cams together and provides the means to draw the bow and propel the arrow. The stored energy is used to propel the arrow when the archer releases the bow string. To achieve peak or maximum performance from the bow, the two eccentric wheels or cams must be synchronized to rotate at the same rate and the same amount during the draw and after release. Synchronization is achieved by setting the cables to the correct lengths. The attachment device that is the subject of this invention will allow the cables to be conveniently and precisely adjusted to synchronize the wheel or cam rotation.
Existing patents found relating to the subject of this patent application:
______________________________________ U.S. Pat. 3,183,565 May 18, 1965 Schwarz U.S. Pat. 4,336,786 June 29, 1982 Mannon et al. U.S. Pat. 4,370,972 February 1, 1983 Stewart et al. U.S. Pat. 4,440,142 April 3, 1984 Simonds U.S. Pat. 4,440,143 April 3, 1984 Nishioka U.S. Pat. 4,448,183 May 15, 1984 Quartino et al. U.S. Pat. 4,733,648 March 29, 1988 Martin U.S. Pat. 4,781,167 November 1, 1988 Martin U.S. Pat. 5,125,389 June 30, 1992 Parr U.S. Pat. 5,307,787 May 3, 1994 LaBorde et al. U.S. Pat. 5,381,777 January 17, 1995 Mitchell et al. ______________________________________
U.S. Pat. Nos. 4,336,786 to Mannon et al. and 4,370,972 to Stewart et al. are for attachment members that secure the ends of the compound bow cables by means of a circuitous pathway and a means of locking the cable in place by a lock screw that provides perpendicular pressure on the cable to displace a portion of that cable into a concavity to provide a firm crimp. The locking action deforms the cable which causes two disadvantages. First, the deformed cable may not freely pass through the attachment member passageways to allow further adjustment; second, the deformation, especially multiple deformation as could occur during adjustment of a bow for peak performance, would weaken the cable increasing the probability of subsequent failure.
U.S. Pat. Nos. 4,440,142 to Simonds and 4,733,648 to Martin provide means to anchor the cable ends to the limb tips of compound bows through the use of a cable loop and without infinite adjustment. Further, the device of Martin, U.S. Pat. No. 4,733,648 includes a locking means that deforms the cable end making subsequent cable length adjustment impractical.
Further, the adjustment of the cables in the attachment members of the above patents requires that cable tension be removed during adjustment. The disadvantage is that adjustment becomes a time consuming, tedious procedure of trial and error activity, in which the cables are adjusted with the tension relieved by adjusting the limb stress or, more likely, by a tool for that purpose, and then the bow is checked for proper adjustment after the tension is reapplied.
Further, the attachment members of the above patents are usable only with steel cables. Many current compound bows use synthetic fiber cables which cannot be attached by those members.
U.S. Pat. Nos. 4,440,143 to Nishioka and 4,448,182 to Quartino et al. show cable attachment devices that use screw adjusters connected to the bow limbs. These require that the cable ends be terminated in special mechanisms to attach to the limbs. U.S. Pat. No. 4,448,182 to Quartino et al. also describes a bracket element that connects to the limb tip axles by means of a cable loop permanently connected to the bracket. Said bracket also requires the cable end be terminated in a special mechanism.
U.S. Pat. No. 4,781,167 to Martin describes an adjustable anchor to secure the ends of the tension cable to the limb tips of a compound bow. The device described requires a cable loop to attach the device to the limb tip axle on both sides of the eccentric wheel or cam, rather than the a single device of the invention disclosed in this application.
U.S. Pat. Nos. 5,125,389 to Paff and 3,183,565 to Schwarz describe mid line adjusters that are usable for tensioning devices temporarily mounted to a compound bow for maintenance purposes. These patents are not directly related to the invention described in this application.
U.S. Pat. No. 5,307,787 to LaBorde describes an anchor bracket that adjusts the position of the end of the compound bow cable parallel to the limb tip axle for the purpose of adjusting limb tip torque. Said anchor bracket does not provide for any adjustment of the effective cable length.
U.S. Pat. No. 5,381,777 to Mitchell et al. describes a yoke mechanism that attaches to the limb tip axle on both sides of the compound bow eccentric wheel or cam by means of two mounting brackets and two cable end segments. The yoke assembly requires that the cable end segments and the end of the tension cable be terminated in a mechanism or element to hold said cable ends in the yoke assembly. The yoke assembly described comprises several elements and is relatively complex.
The attachment device of the invention which is the subject of this application holds the cable end loops commonly employed in compound bows without deformation and with no added stress. The attachment device is designed to hold the looped ends of either steel cables or cables of synthetic fibers. The attachment device can be adjusted with the compound bow cables under tension, which will allow the bow mechanic or archer to conveniently and precisely adjust the cable lengths to achieve peak bow performance without affecting other bow adjustments and without tools to relieve the cable tension.
This invention relates generally to archery bows and particularly to an improved attachment device for securing the ends of the cables in a compound bow using dual eccentric wheels or cams. The present invention is especially adapted for use on compound bows wherein the terminal ends of the eccentric wheel or cam cables are intended to be anchored in the area of the bow limb tips adjacent to the opposite eccentric wheel or cam. Such bows commonly have two such eccentric wheels or cams and possible additional idler wheels about which the cables pass. Unless the bow cable rigging includes a yoke harness or yoke device, one of the most common methods of attaching the cable terminal end to the limb tips has been to form a loop in the terminal end of the cable and place that loop over a grooved spacer around the eccentric axle adjacent to the eccentric wheel or cam. For a steel cable the loop is formed by folding the distal end of the cable back on itself and attaching that end to the same cable by means of a crimped fastener. For a synthetic fiber cable the loop is naturally formed by the method of manufacture from a continuous loop of several strands of small diameter fibers. The end loop is formed by wrapping the strands with fiber serving to hold the strands together and protect them from abrasion. With either steel or synthetic fiber cables the grooved spacer holds the end loop in place but provides no means of adjustment.
Those familiar with the workings of a compound archery bow understand that the proper rigging of the bow with cables and bowstring is critical to the bow performance. Specifically the rigging must place the bow limbs under the correct range of stress and provide the correct balance or synchronization of the eccentric wheels or cams. The wheels or cams must rotate at the same rate as the string is pulled during the archer's drawing the bow, and as the string, wheels or cams and cables return to the rest position as the arrow is propelled forward after the string is released to shoot the arrow. The present invention provides an attachment member to accept the terminal end loop of each of the eccentric wheel or cam cables and connect them to the wheel or cam axles in such a way that the effective cable lengths can be easily adjusted at any point in the drawing of the bow even by an archer in the field. Correct adjustment of the effective cable lengths will result in the synchronization of the two eccentric wheels or cams and peak performance from the bow.
The attachment device consists of three pieces: a body comprising a base element, having two parallel walls attached to said base element defining a slot therebetween to accept and confine the terminal loop of the wheel or cam cable. Near the upper end of each of the parallel walls, said walls have aligned apertures to receive the limb tip axle and thus connect the device to the limb tip. A cable loop support element shaped to support the loop under tension without damaging stress and a threaded adjustment element to adjust the effective cable length. A means of locking the adjustment element in place when properly adjusted is also provided, however different means of locking may be utilized. The device body is relatively thin allowing it to connect to the wheel or cam axle adjacent to the wheel or cam within the space typically allotted for the connection of the cable loop on a grooved spacer. All elements of the attachment device are symmetrical to allow the same device to be used to connect the cable loop at both bow limb tips.
One object of the current invention is to provide an improved compound archery bow cable attachment device to allow convenient adjustment of the effective cable length to synchronize the rotation of the bow eccentric wheel or cams.
Another object of the current invention is to provide an improved compound archery bow cable attachment device to accept either steel cable loops or synthetic fiber cable loops and effectively connect either type of cable to the bow limb tips.
Another object of the current invention is to provide an improved compound archery bow cable attachment device with symmetrical design to allow the same device to be used at both bow limb tips to attach alternate cable ends to the respective limb tips.
Another object of the current invention is to provide an improved compound archery bow cable attachment device of such dimensions as to allow it to replace the grooved spacer used to attach cable ends on many current compound bows so the adjustment feature can be added to bows currently without such convenient adjustment.
With these and other objects in view which will more readily appear as the nature of the invention is better understood, the invention consists in the novel construction, combination and arrangement of parts herein-after more fully described, illustrated and claimed.